Sound-reproducing apparatus



Aug. 12, 1930.

v M. wen.

SOUND REPRODUCING APPARATUS Y s Sheets-Shet 1 Filed Nov. 21, 1922 wm'milialz Mil Aug. 12, 1930. M. wan.

SOUND REPRODUCING APPARATUS Filed Nov. 21, 1922 '5 sheetsasheet 2 r m 1 v W M ).M a n In k a .wzm a m V m AN A/nun? M z 2 a 5 w w A! Patented a... 12, 1930 v UNITED STATES PATENT; orrlcs naxnumnr WEIL, or new 203:, n. it;

SOUND-BEPBODUCING APPARATUS Application filed Iovember fl 1882. Serial Io. 808,884.

My present invention relates to the sound" delivery, more particularly of phonograph apparatus; An object of the invention is to provide apparatus of the above type, which, though en tirely unconfined within a sound proof chainher, will-function to emit the sound with carrying force so small that it'shall be substantially inaudible to the human car at a distance of a few feet from the point of delivery,

and yet shall sound loud at smaller distances without the use of ear tubes or binaurals.

Another object is to provide apparatus o f compact in construction, and easily operable without discomfort to the auditor.

The invention is preferably carried out in a phonograph apparatus having the readily accessible turn table for the record to be traversed by a stylus actuating a diaphragm, all of which elements may be of conventional phonograph design, the sound conduit being however, of special construction. In the preferred embodiment, the sound conduit 1s a tube of internal diameter small preferably less than one-half inch throughout its length from the diaphragm to the delivery opening, the entire length of said conduit bein sound proof, so that the entire emission o vibrations generated in said diaphragm takes place at said delivery opening without'amplificas tion or distortion.

If the ordina sound box were used in this apparatus, the 'aphragmwould at its exsurface, emit sound of appreciable volume, without transmission through the conduit. The sound box is, accordingly, provided with a cover to seal said otherwise exposed Preferably, the sound box cover is disposed at such distance from the diaphragm that the 'volumeof air confined therebetween will serve as a damper upon the diaphragm, decreasing the sound volume transmitted, and reducing the effect of sustained vibration.

'al "substantially air-tight The special sound conduit includes a rigid cylindrical tube carrying the sound box and mounted in the usual manner of a tone arm and incommunication with a flexible conduit 7 element of rubber fabric or the like, the outlet end of which-may be formed-with a short bell,

in the order of two or three inches in diame ter, to be held by the listener at a distance, of a few inches from the ear.

I have shown an embodiment comprising a simple attachment applicable to any ordinary; v

phonograph cabinet or table, equipped wit a record turn table and a driving motor therefor. The attachment consists of a bracket carrying the special pivoted sound box mounting element and theflexible conduit, said bracket to be attached to the cabinet of a conventional phonograph.

The .record being exposed,.as in the usual phonograph, the invention has a particular field of utility as a demonstrator for use in retail phonograph record stores. The customer uses the apparatus by the motor, applying the selected record to the turn table and positioning the stylus in the same manner as in the use of an ordinary phonov graph, thus dispensing with the need for special directions or attendants. By virtue of the low carrying range of the delivery, a plurality of the apparatus may be laced upon a table or counter at intervals as 'ttle as two feet, without incurring disturbance of a lis tener by the performance of a neighboring apparatus.

The invention has a wide r e of further applications, ially where 1t is desired to efiect exceptionally clear rendition of a record for the benefit of only one or a small group of auditors at a time. or instance, the apparatus is of particular value to mus1c cennorsseurs, for effecting a realistic renditlon of a fine selection;- also for preliminary expert testili of records. Other applications are to the p aying of private foreign language instruction records and to private dictation records for instruction of student stenographers, both heretofore played on conventional phonographs.

In the accompanyin drawings in which is shown one or more 0 various possible embodiments of the several features of this invention,

Fig. 1 is a perspective view showing the external appearance of the apparatus in use and the installation thereof.

Fig. 2 is a view in longitudinal cross-section through the conduit, taken along the line 22 of Fig. 1,

Fig. 3 is a view in longitudinal cross-sec tion of the sound delivery handle end,

Fig. 3- is a fragmentary view in longitudinal cross-section of a modification of the sound delivery handle.

Fig. 4 is a transverse sectional view taken along the line 4-4 of Fig. 1,

b Fig. 5 is a plan view of the preferred sound Fig. 6 is a sectional view taken along the line 6-6 of Fig. 5,

Fig. 7 is a sectional view on an enlarged scale taken along the line 7-7 of Fig. 6, and;

Fig. 8 is a side elevation with parts broken away and shown in section of an alternative form of machine.

Referrin now to the drawings, I have shown in ig. 1, the installation and use of my invention as applied for phonograph record demonstration in retail stores. I have shown a counter 1, with a pair of the apparatus A and B spaced by a distance of about two feet. Each apparatus consists of a table phonograph cabinet of substantially conventional construction, having in the interior thereof, the usual motor (not shown) a turn table shaft 2 projecting through the motor board 3 and carrying the turn table 4 upon which is to be mounted the ordinary disk record 5 to be played. My invention in the embodiment shown, comprises an attachment applied to the cabinet in lieu of the usual tone arm, said attachment comprising a pivoted element at the end of which is carried a sound box preferably of special construction to be described below, said attachment also having therein a conduit to be described below, communicating with a flexible sound carrying element 6 at the open end of which is a delivery bell 7 to be held preferably, as shown, at a short distance from the ear.

Coming to the specific construction, the attachment includes a metallic cast-ing having a support plate 8 to be secured as by screws 9 to the side wall of the phonograph cabinet,

said bracket comprising a hub 10, with a stiff ening ri-b structure 11. A vertical cylindrical post 12 projects upward from the hub and a tubular element or pipe 13 projects horizontally toward the right thereof in Fig. 1, the bore 14 of the latter communicating with an axial bore 15 in the post.

In the preferred embodiment, I employ, in lieu of the usual tone arm, a pivoted conduit for carrying the sound box and executing substantially the ordinary movement of the tone arm, as the sound box traverses the record in use. In the preferred embodiment, this element comprises a cylindrical or tubular horizontal member 16 of small diameter, to the end of which may be connected the usual elbow 17 upon which is mounted the sound box 18. Integral with or soldered into a corresponding aperture in the wall of horizontal conduit element 16 is a vertical axle tube 19 which fits telescopically into the upper end of the corresponding bore 15 on the post 12 extending downward for a substantial distance, to prevent leakage of sound, and resting on a shoulder 20 therein. The post 12 of the casting also has preferably a cylindrical cavity 22 between its outer wall and the bearing wall, to reduce weight and to further contribute to sound insulation. The upper end of the bearing 15 is countersunk, as shown, and preferably filled with lubricant 21 to permit substantially frictionless rotation of the axle tube 19 within the bearing in operation. The rear end of the conduit 16 is sealed by a plug 23 having an oblique surface 24, preferably .for directing or reflecting the sound vibrations from the length of the conduit into the axle tube 19. To improve the appearance of the device, an enclosure element 25 is provided for the sound conduit 16, which enclosure preferably has the conventional external form of the usual taper tone arm, although its function is largely ornamental. For assembly, the tube 16 is inserted in an aperture 26 fromed in the rear end of said taper arm enclosure, and soldered in place therein, after which the axle tube 19 is applied and solderedtothe tube 16. The larger or elbow end of the taper arm 25 is partly surrounded by but preferably spaced from a collar 27 encircling the post 12 and coaxial of tube 19, said collar having an integral upstanding arm 28 with a downwardly projecting pin 29 to maintain the taper arm and conduit unit in position.

To obviate any sound emitting vibration of the air confined between the conduit 16 and taper arm 25, the latter is provided with a series of apertures 30, which prevent building up compression waves therein.

In the preferred embodiment, the flexible sound conduit 6 is removably connected to the delivery end of the bore 14 of the support bracket pipe 13. For this purpose, the conduit which is preferably formed of rubber fabric tube, is forced at one end over the corrugated tip 31 of a connecting fitting 32, preferably of brass, a metallic ferrule 33 over the free end of the flexible conduit protecting the edge against fraying. The exposed end of the fitting is exteriorly tapered as at 34, for frictional fit into the correspondingly interiorly tapered outlet end 35 of the bracket pipe 13. If desired, a knurled rosette disk. 36 may be secured as by screws 37 to the free end of the pipe 13 for its ornamental effect.

.At the outer end of the conduit 6, I pref- :rably provide a delivery bell 7 of diameter n the neighborhood of 2 inches and of short length, the mouth 38 of said bell facina at 1.11 angle to the carrying shank thereof. he :ar shank is pre erably a handle to be grasped by the listener and held substanaially vertically as shown in Fig. 1, to dispose zhe bell within a few inches of the ear. The iandle comprises a tube 39 which may be of vulcanite, bakelite or similar material and murled as shown, within the upper end of which is secured as by a screw 40, a sleeve 41 widened at its outer end to form a socket 42 for attachment of the bell 38, the latter being preferably threaded onto a sleeve 43 extendng into socket 42 and secured in lace as )yscrew 44. Although the mouth o bell 38 nay extend at right angles to the length of ;hank 39, I prefer to dispose it, as shown, at m obtuse angle relative thereto to make it ;ubstantially impossible for the auditor to )ress the entire rim of the mouth against his ear so that he cannot prevent interruption of :ommunication between the air column in the tpparatus and the surrounding air, thus avoiding the muflied effect or other distorions which might otherwise be incurred. is an alternative, particularly desirable where the mouth of bell 38' extends at right ingles'to the length of shank 89', one or more tpertures a may be provided in the wall of he bell-to. eliminate the distorting eflects re- ?erred to. When out of use, the handle may e laid on a special tray 45 therefor, projectng be 0nd the lateral edge of the cabinet, and )rovi ed with a finger notch 46.

In the preferred embodiment, the handle is :onnected to the flexible conduit 16 by a :ound-proof couplin designed to permit free *otation of the handle relative to the flexible :lement, so that in use, the flexible conduit vlement will not become twisted. In the pre- Ferred specific embodiment, the deliver end f the conduit is slipped over a fitting 4 simiar to fitting 32 heretofore described, and proected by a ferrule 48. About the free end of aid fitting is a sleeve member 49 having an nturned head 50, arrested by shoulder 51 on itting 47. A screw member 52 hollow from ind to end and having a head 53 of diameter rei'erably equal to the outer diameter of the :leeve 47 extends throu h the free end of :leeve 49 and is threade into the open end f fitting 47, whereby said sleeve is mainained against substantial longitudinal movenent or separation from the fitting, while ree to rotate relative thereto. The screw lead 53 together with the sleeve is inserted nto the open base end of the handle element i9, and one or more. screws 54 through the iandle, serve to secure the sleeve in place herein. When the handle is held in vertical osition in operation, it will be seen that the veight of the flexible conduit tends to draw the screw head 53 downward against the upper end of sleeve 49, for a sound tight seal, the efiectiveness of which is enhanced by a resilient rubber or cork washer 55 at the lower end of the screw head. Should there be any small leakage of sound around the head of the screw and into the interior of sleeve 49, the same will be reflected into the head b the inturned bead 50 and no noticeable le age will occur.

In operation, the sound vibrations are transmitted from the diaphragm through the long small-diameter sound conduit made u of the arm 16, the axle tube 19, the conduit passages 15' and 14- in the bracket and the long rubber fabric flexible conduit 6. The conduit widening nowherein the course of the travel of the sound vibrations therethrough there is no amplification. As heretofore described, substantially no leakage occurs in the length of the conduit, the connections of the axle tube 19 with the bracket, and the couplings at both ends of the flexible conduit being substantially sound leak roof. In the preferred embodiment, the con uit is of such length that an appreciable fraction of the energy is absorbed by the walls, particularly of the flexible conduit 6, so that the sound emerges from the bell 38 mellowed and with small volume and carrying force, to limit the audibility thereof to a short range. The sound vibrations afterpassing through the long restricted conduit in the absence of the delivery bell may be essentially unidirectional, so that difliculty might arise in disposing and maintaining the outlet within the range of audibility of the listener. By reason of the s reading or diver 'ng emission resulting Tom the use of t e flaring bell, the sound is audible throughout a wider area within the limited range of audibility, so that two or'more persons may readily listen at the same time.

If an ordinary sound box were used in a device of thistype, the diaphragm may -emit sound of volume and carryin force in excess of that desired, both throng the conduit and at the exposed surface of the diaphragm, so that the delivery of the instrument, as a whole, would have relatively wide carrying force and could not be used to best advanta e for 1.1. purpose.

In or er to eliminate this, I employ a special sound box now to be described. This sound box includes the usual ring or annulus 56 for the usual diaphragm 57 maintained in place in the ordinary manner between a pair of gaskets 58. The ring has the usual fitting 59 for attachment to the elbow 17 forming a part of the usual tone arm construction and serving, in my embodiment, to convey the vibrations from the diaphragm to the conduit pipe 16. The stylus 60 is clamped by screw 61 to the usual stylus lever 62 pivotally mounted at 63 in the usual manner, and connected at its end to the center of the diaphragm 57 by a small quantity of bees wax 64, as is shown. The exposed side of the dia phragm that is, the left side thereof in Fig. 6, is preferably closed air-tight by means of a metallic closure preferably in the form of a cap having a flange 66 secured to the ring by screws 67, an interposed gasket 68 establishing an air-tight connection. The flange 66 has an aperture 69 through which the stylus lever extends with small clearance, in the order of 1 mm., said aperture being sealed with a small quantity of bees wax 70, to prevent leakage therethrough without, however, interfering with the freedom of vibration of the stylus lever in use. Thus, the cap 65, diaphragm 57 and intervening ring andflange elements 56 and 68 constitute an air-tight closed or sealed chamber 71 filled with air, preferably under atmospheric pressure.

For installation of the attachment upon the ordinary phonograph, the ordinary tone arm is removed and inits stead the castinging bracket is screwed to the side of the cabinet, the throat of the usual amplifier (not shown) being preferably sealed as well as the doors or other closing means in front thereof.

The flexible conduit 6 is applied by inserting the tapered plug end of brass fitting 32 into the corresponding socket aperture 35 in the casting bracket for tight frictional en gagement. The machine and record are operated in the same manner as in an ordinary phonograph. The spring motor is wound in the usual way, the selected record is placed upon the turn table and the stylus on the sound box is brought into engagement with the extreme groove of the record. The pivot ed conduit having the conventional external form of the familiar taper tone arm, the user of an ordinary phonograph will at once know how to use my apparatus, without necessity for instructions or directions.

The energy from the diaphragm, it will be noted, is transmitted from the sound box through the elbow element 17 through the length of tubular conduit 16 deflected at right angles thereto, downward through the axle tube 19 and through vertical conduit 15 and horizontal conduit 14 within the bracket casting, thence past the friction coupling 34-35, through the length of the rubber fabric conduit 6, for delivery at the bell 38, as shown in Fig. 1, which is held by the hand at a few inches from the ear or may be placed in a suitable holder, if desired. By reason of the sound insulating effect of the cap 65 in the sound box, no appreciable part of the vibratory energy of the diapragm escapes direct to the air, the vibratory energy thereof being substantially all transmitted toward the bellat the end of the conduit. The enclosing air chamber 71 to the rear of the dia phragm, acts, moreover, as a damper to restantially sound leak proof, so that sound emission in advance of the bell which might be of greater carrying force than at the bell is avoided. Thus, the vibratory diaphragm transmits its damped vibrations through the length of the conduit without amplification, and in the flexible element 6 more particularly, energy is absorbed to soften or render mellow the emitted sound. More specifically, the diaphragm 57 which produces the vibrations is substantially sealed at one side thereof, and transmits its vibrations through a substantially sound-tight damping conduit. The sound absorbing effect of the conduit, of course, depends upon the material of which it is constructed and the length and diameter, so that the intensity of the sound emitted may be predetermined. In the preferred use for phonograph record demonstrating apparatus, the sound, as heretofore noted, should have a carrying force sufiicient to be audible at a short range only and of intensity insufficient for effective amplification even if an amplifying horn be substituted for the delivery bell. In the preferred embodiment, the flexible conduit is about in diameter and from 30 to 45 inches in length, the metallic conduit elements being preferably somewhat lar er in diameter, although it will be understoo that satisfactory results may be obtained with the parts of other dimensions.

In the use of my apparatus to play a disk record of the usual type, the performance seems relatively loud within a range of about one foot from the bell, but is substantially inaudible therebeyond. The delivery is surprisingly clear and realistic, recreating with their proper value, tone elements on the record apparently, lost in performance on an ordinary phonograph.

It will be seen that, the apparatus when employed in retail phonograph stores, for record demonstration requires much less room and avoids the unsanitary feature of the ordinary enclosed booth. The apparatus may be disposed on a table or counter, as little as two feet apart, each customer handling and playing records, as he would on his own phonograph without disturbance by the performance of the neighboring apparatus. The-normal use of the apparatus, it will be noted, does not require the removal of the customers hat, or the disarrangement of her hair incurred with-apparatus requiring ear'tubes or binaurals. The'annoyanc'e of a twisted flexible conduit is, moreover, entirely obviated by reason of the freely rotatable coupling. I

, Fig. 8 illustrates an alternative embodiment, showing another modification of an ordinary phonograph to adapt it to my purpose. In this case, I employ the same sound convey 'ing tube 16, heretofore described, .with its axle tube 19' at right angles thereto and enclosed within the conventional tapered tone arm structure 25, perforated as at 30. The taper element is mounted directly on top of the phonograph table with the usual pivotal mount 72. The axle tube 19 unlike the embodiment of Figs. 1 to 7, 'doesnot fit into a bearing, but extends freely downward into the neck of the amplifier 73, the taper arm 'pivot 72 serving as the bearing for the conduit. To the lower end of vertical tube 19, a flexible rubber fabric conduit 7 4 is attached in an appropriate manner to provide a leak proo coupling, said flexible conduit extending through the amplifier and being provided with a terminal opening 75, preferably in one of the side walls of the cabinet, to be plugged witha flexible conduit element similar to that shown-in Fig. 1. The sound vibrations, it will be seen, traverse the sound proof flexible conduit without leak into the amplifier, so that the latter does not function. If desired, however, the amplifier may be removed or sealed.

' As heretoforesuggested, the invention is not limited in its application to the demonstratiou of phonogra h records in record dispensing retail stores, ut has a broad range of applications, particularly where the selection is to be produced for the benefit of one or a small group of persons at a time. By reason of the remarkably clear and distinct production inherentin my apparatus, it has particular utility, moreover, for the playing of fine musical selections, where the original is desired to be reproduced with exceptional distinctness, regardless of volume. Other applications are to the expert testing of phono graph records, the playing of foreign language instruction records and to the disk dictation records for use in regular phonegraphs by stenography students.

.ZAlthough my. preferred form of sound box has its preferred application to a low-volume non-amplifying phonograph apparatus of the character described, it is not limited in its application to this apparatus, but may be sub-.

' stitutedforan ordinary sound box in an ordinary phonograph. As a result of such sub- ":stitution, while the volume of the phonograph i is reduced somewhat,its distinctness and clear- .Eness :ismarkedly enhanced. This is a con- ,i's'e name, as heretofore noted, of the dampin ue ectfu on. the dia hragm of the sealed vo r-ume o stair/there hind which, moreover,

eliminates overlapping and interference between successive sounds.

I claim 1. A phonograph apparatus of the type includin a casing element, a motor, a turn table s aft, a turn table thereon for rotating adisk record of usual construction in which the'turn table is exposed with respect to the auditor during operation, a rigid sound conduit element movably supported at one end upon said casin a sound box carried at the free endof said element having a stylus for traversing the length of the record groove, and having a cover element for effecting an air-tight seal of the otherwise exposed surface of said diaphragm; the combination therewith, of a relatively long vi bration absorbing conduit of small diameter communicating with said rigid conduit for transmitting vibrations enerated in said diaphragm, said conduit a-ving a delivery bell of small diameter at its open end.

2. In a phonogra h, of the type includin a cabinet, a turn ta le for carrying a recor exposed during 0 eration, a cylindrical rigid sound conduit 0 small diameter pivotally mounted with respect to said cabinet, a sound box carried at the free end thereof for coaction with the record grooves, said sound box having a substantially air-tight seal for the otherwise ex osed side of the diaphragm.

thereof; the com ination therewith o a flexible vibration absorbing sound conduit in communication with the rigid conduit element, and of relatively small diameter and substantial length, a sound delivery bell of small diameter at the free end thereof, and means for sustaining said bell in proximity to the head of the listener.

3. In phonographic apparatus, in combination, a substantially sound proof conduit of substantially uniform diameter from end to end for connection between the diaphragm of a sound box and a mouth member, said conduit including a rigid tubular element to carry the sound box at the free end thereof, a substantially vertical tubular axle therefor at the end opposite said sound box and in communication with the interior of said rigid tubular element, a flexible vibration absorbin conduit element in communication with said tubular axle member, and a sound delivery element of small diameter at the free end of said flexible conduit.

4. In phonographic apparatus, in combi nation, a horizontal tubular sound conduit, a vertical pivotally mounted axle tube in rigid communication therewith, and a fixed bearing post therefor including a vertical bearing portion of substantial length, a considerable len h of said tube bearm in said fixed post, said post having a soun insulating air space therein about said bearing.

5. In phone aphic apparatus, in combination, an em: osing element of the usual III nation, a cylindrical sound conduit element of small diameter, imperforate from end to end thereof, a sound box carried at one end thereof, and an enclosure for said conduit element, said enclosure having the external appearance and the pivotal mount of a ph'onograph taper tone arm, and means rigidly connecting said conduit element Within said enclosure.

8. In phonographic apparatus, in combination, a casting having an elongated vertical bearing, a tubular axis element extending into said vertical bearing, a substantially horizontal sound conduit element rigid and communicating with said axis element, a sound box at the free end of saidhorizontal element and in communication therewith, and an element having the usual external conformationof a tone arm enclosing said horizontal conduit, and having a pivotal mount coaxial of said tubuiar axis element, said enclosing element having apertures to relieve compression therein.

9. In a phonograph record demonstrating apparatus, in combination, a sound box, a handle element having a small delivery opening to be held in proximit to the head of the listener, a flexible soun conduit element, means connecting said element with said sound box at one end and to said handle element at the other, said connecting means being substantially proof against leakage of sound, the connecting means at one end of said conduit allowing free relative rotary displacement, whereby the flexible conduit will remain untwisted in handling.

10. A record demonstrating attachment for phonograph cabinets, comprising a bracket casting having means for attachment to the s1de of the cabinet and an integral vertical bearing post, a movable conduit member com- PI IS1I1g a vertical axle tube extending into sald bearing ost and a substantially horizontal tubular e ement rigid with and in communication with the upper end of-said axle tube, a sound box carried at the free end of said tubular element, said sound box having a substantially sound-tight closure at the side 7 thereof otherwise exposed, said bracket having a conduit therethrough in communication with the lower end of said axle tube for attachment of a flexible conduit to the free end thereof.

11. In a demonstrating apparatus for phonographs, in combination, a bracket casting having an integral plate, for attachment to the side of a phonograph cabinet, said casting including a vertical conduit post and a horizontal conduit pipe communicating therewith, a vertical tubular axle element extending into the conduit post of said bracket and having rigid therewith a horizontal cylindrical conduit element for carrying a sound box, said horizontal conduit pipe having means for coupling of a flexible sound conduit thereto.

12. In a phonograph apparatus, in combination, an enclosure having the conventional tone arm exterior, a tubular sound. conduit fixed longitudinally therein, a sound box carried at the free end thereof in air tight communication therewith, a hollow pivot mount for said conduit and a conduit having a flexible element communicating with said pivot mount and terminating at the wall of said phonograph, whereby upon attachment of said conduit element at said wall, the sound vibrations will be communicated thereto through the length of said conduit and of said hollow pivot mount.

13. In a phonograph apparatus of the type comprising a turn table for a disk record exposed during operation, a conduit element movable about a vertical hollow pivot axis, a sound box carried thereb and movable therewith across the recor the combination therewith of a flexible vibration absorbing substantially sound-tight conduit element of diameter smaller than said sound box for substantially the entire lengththereof, and a substantially sound proof detachable cou pling between an end of said second conduit element and thepivoted end of said first conduit element.

14. In a phonograph apparatus, in combination, an exposed sound box, cover means carried by said sound box substantially sealing one side thereof and a. substantially sound-tight conduit of diameter smaller than that of said sound box throughout the length thereof, and of length and construction to effect sound dampening in order to emit the vibrations for small carrying range thereof.

15. In a phonograph of the type comprising an exposed turn table for carrying a disk record, a tone arm, a sound box carried thereby and having a stylus for coaction with the record, and means substantially sealing one side of said sound box; the combination therewith of a substantially sound-tight conduit of small diameter throughout the length thereof for transmitting the vibrations from said tone arm to the auditor, the len th of said conduit being of material sound a sorbing to such extent as to reduce the carrying force of sound emitted therefrom to an efiective range, so low as to avoid disturbance between two similar instruments operating close to one another in the same room.

- Signed at New York, in the county of New York and State of New York this 20th day of November, 1922.

MAXIMILIAN 

